From 2ccece32253171ccc75f21f1d1c14ea554dadfb9 Mon Sep 17 00:00:00 2001
From: Niels <nnmvdw@gmail.com>
Date: Wed, 2 Aug 2017 11:40:03 +0200
Subject: [PATCH] Splitted cons_repr

---
 FiniteSets/_CoqProject                  |   6 +-
 FiniteSets/fsets/extensionality.v       | 194 ++++-----
 FiniteSets/fsets/isomorphism.v          |  69 +++
 FiniteSets/fsets/length.v               |  40 ++
 FiniteSets/fsets/operations_cons_repr.v |  19 +
 FiniteSets/fsets/properties_cons_repr.v |  75 ++++
 FiniteSets/implementations/lists.v      |   6 +-
 FiniteSets/representations/bad.v        | 538 ++++++++++++------------
 FiniteSets/representations/cons_repr.v  | 415 +++++-------------
 FiniteSets/representations/definition.v | 317 +++++++-------
 10 files changed, 840 insertions(+), 839 deletions(-)
 create mode 100644 FiniteSets/fsets/isomorphism.v
 create mode 100644 FiniteSets/fsets/length.v
 create mode 100644 FiniteSets/fsets/operations_cons_repr.v
 create mode 100644 FiniteSets/fsets/properties_cons_repr.v

diff --git a/FiniteSets/_CoqProject b/FiniteSets/_CoqProject
index aa0f7e5..aa99194 100644
--- a/FiniteSets/_CoqProject
+++ b/FiniteSets/_CoqProject
@@ -4,14 +4,18 @@ lattice.v
 disjunction.v
 representations/bad.v
 representations/definition.v
+representations/cons_repr.v
+fsets/operations_cons_repr.v
+fsets/properties_cons_repr.v
+fsets/isomorphism.v
 fsets/operations.v
 fsets/properties.v
 fsets/operations_decidable.v
 fsets/extensionality.v
 fsets/properties_decidable.v
+fsets/length.v
 fsets/monad.v
 FSets.v
-representations/cons_repr.v
 implementations/lists.v
 variations/enumerated.v
 #empty_set.v
diff --git a/FiniteSets/fsets/extensionality.v b/FiniteSets/fsets/extensionality.v
index 838afb9..d730474 100644
--- a/FiniteSets/fsets/extensionality.v
+++ b/FiniteSets/fsets/extensionality.v
@@ -4,108 +4,108 @@ From representations Require Import definition.
 From fsets Require Import operations properties.
 
 Section ext.
-Context {A : Type}.
-Context `{Univalence}.
+  Context {A : Type}.
+  Context `{Univalence}.
 
-Lemma subset_union_equiv
-  : forall X Y : FSet A, subset X Y <~> U X Y = Y.
-Proof.
-  intros X Y.
-  eapply equiv_iff_hprop_uncurried.
-  split.
-  - apply subset_union.
-  - intro HXY.
-    rewrite <- HXY.
-    apply subset_union_l.
-Defined.
-
-Lemma subset_isIn (X Y : FSet A) :
-  (forall (a : A), isIn a X -> isIn a Y)
-  <~> (subset X Y).
-Proof.
-  eapply equiv_iff_hprop_uncurried.
-  split.
-  - hinduction X ;
-      try (intros; repeat (apply path_forall; intro); apply equiv_hprop_allpath ; apply _).
-    + intros ; reflexivity.
-    + intros a f.
-      apply f.
-      apply tr ; reflexivity.
-    + intros X1 X2 H1 H2 f.
-      enough (subset X1 Y).
-      enough (subset X2 Y).
-      { split. apply X. apply X0. }
-      * apply H2.
-        intros a Ha.
-        apply f.
-        apply tr.
-        right.
-        apply Ha.
-      * apply H1.
-        intros a Ha.
-        apply f.
-        apply tr.
-        left.
-        apply Ha.
-  - hinduction X ;
-      try (intros; repeat (apply path_forall; intro); apply equiv_hprop_allpath ; apply _).
-    + intros. contradiction.
-    + intros b f a.
-      simple refine (Trunc_ind _ _) ; cbn.
-      intro p.
-      rewrite p^ in f.
-      apply f.
-    + intros X1 X2 IH1 IH2 [H1 H2] a.
-      simple refine (Trunc_ind _ _) ; cbn.
-      intros [C1 | C2].
-      ++ apply (IH1 H1 a C1).
-      ++ apply (IH2 H2 a C2).
-Defined.
-
-(** ** Extensionality proof *)
-
-Lemma eq_subset' (X Y : FSet A) : X = Y <~> (U Y X = X) * (U X Y = Y).
-Proof.
-  unshelve eapply BuildEquiv.
-  { intro H'. rewrite H'. split; apply union_idem. }
-  unshelve esplit.
-  { intros [H1 H2]. etransitivity. apply H1^.
-    rewrite comm. apply H2. }
-  intro; apply path_prod; apply set_path2. 
-  all: intro; apply set_path2.  
-Defined.
-
-Lemma eq_subset (X Y : FSet A) :
-  X = Y <~> (subset Y X * subset X Y).
-Proof.
-  transitivity ((U Y X = X) * (U X Y = Y)).
-  apply eq_subset'.
-  symmetry.
-  eapply equiv_functor_prod'; apply subset_union_equiv.
-Defined.
-
-Theorem fset_ext (X Y : FSet A) :
-  X = Y <~> (forall (a : A), isIn a X = isIn a Y).
-Proof.
-  refine (@equiv_compose' _ _ _ _ _) ; [ | apply eq_subset ].
-  refine (@equiv_compose' _ ((forall a, isIn a Y -> isIn a X)
-                             *(forall a, isIn a X -> isIn a Y)) _ _ _).
-  - apply equiv_iff_hprop_uncurried.
+  Lemma subset_union_equiv
+    : forall X Y : FSet A, subset X Y <~> U X Y = Y.
+  Proof.
+    intros X Y.
+    eapply equiv_iff_hprop_uncurried.
     split.
-    * intros [H1 H2 a].
-      specialize (H1 a) ; specialize (H2 a).
-      apply path_iff_hprop.
-      apply H2.
-      apply H1.
-    * intros H1.
-      split ; intro a ; intro H2.
+    - apply subset_union.
+    - intro HXY.
+      rewrite <- HXY.
+      apply subset_union_l.
+  Defined.
+
+  Lemma subset_isIn (X Y : FSet A) :
+    (forall (a : A), isIn a X -> isIn a Y)
+      <~> (subset X Y).
+  Proof.
+    eapply equiv_iff_hprop_uncurried.
+    split.
+    - hinduction X ;
+        try (intros; repeat (apply path_forall; intro); apply equiv_hprop_allpath ; apply _).
+      + intros ; reflexivity.
+      + intros a f.
+        apply f.
+        apply tr ; reflexivity.
+      + intros X1 X2 H1 H2 f.
+        enough (subset X1 Y).
+        enough (subset X2 Y).
+        { split. apply X. apply X0. }
+        * apply H2.
+          intros a Ha.
+          apply f.
+          apply tr.
+          right.
+          apply Ha.
+        * apply H1.
+          intros a Ha.
+          apply f.
+          apply tr.
+          left.
+          apply Ha.
+    - hinduction X ;
+        try (intros; repeat (apply path_forall; intro); apply equiv_hprop_allpath ; apply _).
+      + intros. contradiction.
+      + intros b f a.
+        simple refine (Trunc_ind _ _) ; cbn.
+        intro p.
+        rewrite p^ in f.
+        apply f.
+      + intros X1 X2 IH1 IH2 [H1 H2] a.
+        simple refine (Trunc_ind _ _) ; cbn.
+        intros [C1 | C2].
+        ++ apply (IH1 H1 a C1).
+        ++ apply (IH2 H2 a C2).
+  Defined.
+
+  (** ** Extensionality proof *)
+
+  Lemma eq_subset' (X Y : FSet A) : X = Y <~> (U Y X = X) * (U X Y = Y).
+  Proof.
+    unshelve eapply BuildEquiv.
+    { intro H'. rewrite H'. split; apply union_idem. }
+    unshelve esplit.
+    { intros [H1 H2]. etransitivity. apply H1^.
+      rewrite comm. apply H2. }
+    intro; apply path_prod; apply set_path2. 
+    all: intro; apply set_path2.  
+  Defined.
+
+  Lemma eq_subset (X Y : FSet A) :
+    X = Y <~> (subset Y X * subset X Y).
+  Proof.
+    transitivity ((U Y X = X) * (U X Y = Y)).
+    apply eq_subset'.
+    symmetry.
+    eapply equiv_functor_prod'; apply subset_union_equiv.
+  Defined.
+
+  Theorem fset_ext (X Y : FSet A) :
+    X = Y <~> (forall (a : A), isIn a X = isIn a Y).
+  Proof.
+    refine (@equiv_compose' _ _ _ _ _) ; [ | apply eq_subset ].
+    refine (@equiv_compose' _ ((forall a, isIn a Y -> isIn a X)
+                               *(forall a, isIn a X -> isIn a Y)) _ _ _).
+    - apply equiv_iff_hprop_uncurried.
+      split.
+      * intros [H1 H2 a].
+        specialize (H1 a) ; specialize (H2 a).
+        apply path_iff_hprop.
+        apply H2.
+        apply H1.
+      * intros H1.
+        split ; intro a ; intro H2.
       + rewrite (H1 a).
         apply H2.
       + rewrite <- (H1 a).
         apply H2.
-  - eapply equiv_functor_prod' ;
-    apply equiv_iff_hprop_uncurried ;
-    split ; apply subset_isIn.
-Defined.
+    - eapply equiv_functor_prod' ;
+        apply equiv_iff_hprop_uncurried ;
+        split ; apply subset_isIn.
+  Defined.
 
 End ext.
diff --git a/FiniteSets/fsets/isomorphism.v b/FiniteSets/fsets/isomorphism.v
new file mode 100644
index 0000000..253b433
--- /dev/null
+++ b/FiniteSets/fsets/isomorphism.v
@@ -0,0 +1,69 @@
+(* The representations [FSet A] and [FSetC A] are isomorphic for every A *)
+Require Import HoTT HitTactics.
+From representations Require Import cons_repr definition.
+From fsets Require Import operations_cons_repr properties_cons_repr.
+
+Section Iso.
+
+  Context {A : Type}.
+  Context `{Univalence}.
+
+  Definition FSetC_to_FSet: FSetC A -> FSet A.
+  Proof.
+    hrecursion.
+    - apply E.
+    - intros a x. apply (U (L a) x).
+    - intros. cbn.  
+      etransitivity. apply assoc.
+      apply (ap (fun y => U y x)).
+      apply idem.
+    - intros. cbn.
+      etransitivity. apply assoc.
+      etransitivity. refine (ap (fun y => U y x) _ ).
+      apply FSet.comm.
+      symmetry. 
+      apply assoc.
+  Defined.
+
+  Definition FSet_to_FSetC: FSet A -> FSetC A :=
+    FSet_rec A (FSetC A) (FSetC.trunc A) Nil singleton append append_assoc 
+             append_comm append_nl append_nr singleton_idem.
+
+  Lemma append_union: forall (x y: FSetC A), 
+      FSetC_to_FSet (append x y) = U (FSetC_to_FSet x) (FSetC_to_FSet y).
+  Proof.
+    intros x. 
+    hrecursion x; try (intros; apply path_forall; intro; apply set_path2).
+    - intros. symmetry. apply nl.
+    - intros a x HR y. rewrite HR. apply assoc.
+  Defined.
+
+  Lemma repr_iso_id_l: forall (x: FSet A), FSetC_to_FSet (FSet_to_FSetC x) = x.
+  Proof.
+    hinduction; try (intros; apply set_path2).
+    - reflexivity.
+    - intro. apply nr.
+    - intros x y p q. rewrite append_union, p, q. reflexivity.
+  Defined.
+
+
+  Lemma repr_iso_id_r: forall (x: FSetC A), FSet_to_FSetC (FSetC_to_FSet x) = x.
+  Proof.
+    hinduction; try (intros; apply set_path2).
+    - reflexivity.
+    - intros a x HR. rewrite HR. reflexivity.
+  Defined.
+
+
+  Theorem repr_iso: FSet A <~> FSetC A.
+  Proof.
+    simple refine (@BuildEquiv (FSet A) (FSetC A) FSet_to_FSetC _ ).
+    apply isequiv_biinv.
+    unfold BiInv. split.
+    exists FSetC_to_FSet.
+    unfold Sect. apply repr_iso_id_l.
+    exists FSetC_to_FSet.
+    unfold Sect. apply repr_iso_id_r.
+  Defined.
+
+End Iso.
\ No newline at end of file
diff --git a/FiniteSets/fsets/length.v b/FiniteSets/fsets/length.v
new file mode 100644
index 0000000..c2aa64d
--- /dev/null
+++ b/FiniteSets/fsets/length.v
@@ -0,0 +1,40 @@
+(* The length function for finite sets *)
+Require Import HoTT HitTactics.
+From representations Require Import cons_repr definition.
+From fsets Require Import operations_decidable isomorphism properties_decidable.
+
+Section Length.
+
+  Context {A : Type}.
+  Context {A_deceq : DecidablePaths A}.
+  Context `{Univalence}.
+
+  Opaque isIn_b.
+
+  Definition length (x: FSetC A) : nat.
+  Proof.
+    simple refine (FSetC_ind A _ _ _ _ _ _ x ); simpl.
+    - exact 0.
+    - intros a y n. 
+      pose (y' := FSetC_to_FSet y).
+      exact (if isIn_b a y' then n else (S n)).
+    - intros. rewrite transport_const. cbn.
+      simplify_isIn. simpl. reflexivity.
+    - intros. rewrite transport_const. cbn.
+      simplify_isIn.
+      destruct (dec (a = b)) as [Hab | Hab].
+      + rewrite Hab. simplify_isIn. simpl. reflexivity.
+      + rewrite ?L_isIn_b_false; auto. simpl. 
+        destruct (isIn_b a (FSetC_to_FSet x0)), (isIn_b b (FSetC_to_FSet x0)) ; reflexivity.
+        intro p. contradiction (Hab p^).
+  Defined.
+
+  Definition length_FSet (x: FSet A) := length (FSet_to_FSetC x).
+
+  Lemma length_singleton: forall (a: A), length_FSet (L a) = 1.
+  Proof. 
+    intro a.
+    cbn. reflexivity. 
+  Defined.
+
+End Length.
\ No newline at end of file
diff --git a/FiniteSets/fsets/operations_cons_repr.v b/FiniteSets/fsets/operations_cons_repr.v
new file mode 100644
index 0000000..1ac1482
--- /dev/null
+++ b/FiniteSets/fsets/operations_cons_repr.v
@@ -0,0 +1,19 @@
+(* Operations on [FSetC A] *)
+Require Import HoTT HitTactics.
+Require Import representations.cons_repr.
+
+Section operations.
+
+  Context {A : Type}.
+
+  Definition append  (x y: FSetC A) : FSetC A.
+    hinduction x.
+    - apply y.
+    - apply Cns.
+    - apply dupl.
+    - apply comm.
+  Defined.
+
+  Definition singleton (a:A) : FSetC A := a;;∅.
+
+End operations.
\ No newline at end of file
diff --git a/FiniteSets/fsets/properties_cons_repr.v b/FiniteSets/fsets/properties_cons_repr.v
new file mode 100644
index 0000000..5efa948
--- /dev/null
+++ b/FiniteSets/fsets/properties_cons_repr.v
@@ -0,0 +1,75 @@
+(* Properties of the operations on [FSetC A] *)
+Require Import HoTT HitTactics.
+Require Import representations.cons_repr.
+From fsets Require Import operations_cons_repr.
+
+Section properties.
+  Context {A : Type}.
+
+  Lemma append_nl: 
+    forall (x: FSetC A), append ∅ x = x. 
+  Proof.
+    intro. reflexivity.
+  Defined.
+
+  Lemma append_nr: 
+    forall (x: FSetC A), append x ∅ = x.
+  Proof.
+    hinduction; try (intros; apply set_path2).
+    -  reflexivity.
+    -  intros. apply (ap (fun y => a ;; y) X).
+  Defined.
+  
+  Lemma append_assoc {H: Funext}:  
+    forall (x y z: FSetC A), append x (append y z) = append (append x y) z.
+  Proof.
+    intro x; hinduction x; try (intros; apply set_path2).
+    - reflexivity.
+    - intros a x HR y z. 
+      specialize (HR y z).
+      apply (ap (fun y => a ;; y) HR). 
+    - intros. apply path_forall. 
+      intro. apply path_forall. 
+      intro. apply set_path2.
+    - intros. apply path_forall.
+      intro. apply path_forall. 
+      intro. apply set_path2.
+  Defined.
+  
+  Lemma append_singleton: forall (a: A) (x: FSetC A), 
+      a ;; x = append x (a ;; ∅).
+  Proof.
+    intro a. hinduction; try (intros; apply set_path2).
+    - reflexivity.
+    - intros b x HR. refine (_ @ _).
+      + apply comm.
+      + apply (ap (fun y => b ;; y) HR).
+  Defined.
+
+  Lemma append_comm {H: Funext}: 
+    forall (x1 x2: FSetC A), append x1 x2 = append x2 x1.
+  Proof.
+    intro x1. 
+    hinduction x1;  try (intros; apply set_path2).
+    - intros. symmetry. apply append_nr. 
+    - intros a x1 HR x2.
+      etransitivity.
+      apply (ap (fun y => a;;y) (HR x2)).  
+      transitivity  (append (append x2 x1) (a;;∅)).
+      + apply append_singleton. 
+      + etransitivity.
+    	* symmetry. apply append_assoc.
+    	* simple refine (ap (fun y => append x2 y) (append_singleton _ _)^).
+    - intros. apply path_forall.
+      intro. apply set_path2.
+    - intros. apply path_forall.
+      intro. apply set_path2.  
+  Defined.
+
+  Lemma singleton_idem: forall (a: A), 
+      append (singleton a) (singleton a) = singleton a.
+  Proof.
+    unfold singleton. intro. cbn. apply dupl.
+  Defined.
+
+End properties.
diff --git a/FiniteSets/implementations/lists.v b/FiniteSets/implementations/lists.v
index cb96c89..2994b41 100644
--- a/FiniteSets/implementations/lists.v
+++ b/FiniteSets/implementations/lists.v
@@ -1,5 +1,7 @@
+(* Implementation of [FSet A] using lists *)
 Require Import HoTT HitTactics.
 Require Import representations.cons_repr FSets.
+From fsets Require Import operations_cons_repr isomorphism length.
 
 Section Operations.
   Variable A : Type.
@@ -80,7 +82,7 @@ Section ListToSet.
   Defined.
 
   Lemma append_FSetCappend (l1 l2 : list A) :
-    list_to_setC (append l1 l2) = FSetC.append (list_to_setC l1) (list_to_setC l2).
+    list_to_setC (append l1 l2) = operations_cons_repr.append (list_to_setC l1) (list_to_setC l2).
   Proof.
     induction l1 ; simpl in *.
     - reflexivity.
@@ -117,7 +119,7 @@ Section ListToSet.
   Defined.
   
   Lemma length_sizeC (l : list A) :
-    cardinality l = cons_repr.length (list_to_setC l).
+    cardinality l = length (list_to_setC l).
   Proof.
     induction l.
     - cbn.
diff --git a/FiniteSets/representations/bad.v b/FiniteSets/representations/bad.v
index e54c229..e0abc6c 100644
--- a/FiniteSets/representations/bad.v
+++ b/FiniteSets/representations/bad.v
@@ -4,188 +4,188 @@
 Require Import HoTT.
 Require Import HitTactics.
 Module Export FSet.
- 
-Section FSet.
-Variable A : Type.
-
-Private Inductive FSet : Type :=
-  | E : FSet
-  | L : A -> FSet
-  | U : FSet -> FSet -> FSet.
-
-Notation "{| x |}" :=  (L x).
-Infix "∪" := U (at level 8, right associativity).
-Notation "∅" := E.
-
-Axiom assoc : forall (x y z : FSet ),
-  x ∪ (y ∪ z) = (x ∪ y) ∪ z.
-
-Axiom comm : forall (x y : FSet),
-  x ∪ y = y ∪ x.
-
-Axiom nl : forall (x : FSet),
-  ∅ ∪ x = x.
-
-Axiom nr : forall (x : FSet),
-  x ∪ ∅ = x.
-
-Axiom idem : forall (x : A),
-  {| x |} ∪ {|x|} = {|x|}.
-
-End FSet.
-
-Arguments E {_}.
-Arguments U {_} _ _.
-Arguments L {_} _.
-Arguments assoc {_} _ _ _.
-Arguments comm {_} _ _.
-Arguments nl {_} _.
-Arguments nr {_} _.
-Arguments idem {_} _.
-
-Section FSet_induction.
-Variable A: Type.
-Variable  (P : FSet A -> Type).
-Variable  (eP : P E).
-Variable  (lP : forall a: A, P (L a)).
-Variable  (uP : forall (x y: FSet A), P x -> P y -> P (U x y)).
-Variable  (assocP : forall (x y z : FSet A) 
-                   (px: P x) (py: P y) (pz: P z),
-  assoc x y z #
-   (uP      x    (U y z)          px        (uP y z py pz)) 
-  = 
-   (uP   (U x y)    z       (uP x y px py)          pz)).
-Variable  (commP : forall (x y: FSet A) (px: P x) (py: P y),
-  comm x y #
-  uP x y px py = uP y x py px).
-Variable  (nlP : forall (x : FSet A) (px: P x), 
-  nl x # uP E x eP px = px).
-Variable  (nrP : forall (x : FSet A) (px: P x), 
-  nr x # uP x E px eP = px).
-Variable  (idemP : forall (x : A), 
-  idem x # uP (L x) (L x) (lP x) (lP x) = lP x).
-
-(* Induction principle *)
-Fixpoint FSet_ind
-  (x : FSet A)
-  {struct x}
-  : P x
-  := (match x return _ -> _ -> _ -> _ -> _ -> P x with
-        | E => fun _ => fun _ => fun _ => fun _ => fun _ => eP
-        | L a => fun _ => fun _ => fun _ => fun _ => fun _ => lP a
-        | U y z => fun _ => fun _ => fun _ => fun _ => fun _ => uP y z
-           (FSet_ind y)
-           (FSet_ind z)
-      end) assocP commP nlP nrP idemP.
-
-
-Axiom FSet_ind_beta_assoc : forall (x y z : FSet A),
-  apD FSet_ind (assoc x y z) =
-  (assocP x y z (FSet_ind x)  (FSet_ind y) (FSet_ind z)).
-
-Axiom FSet_ind_beta_comm : forall (x y : FSet A),
-  apD FSet_ind (comm x y) = (commP x y (FSet_ind x) (FSet_ind y)).
-
-Axiom FSet_ind_beta_nl : forall (x : FSet A),
-  apD FSet_ind (nl x) = (nlP x (FSet_ind x)).
-
-Axiom FSet_ind_beta_nr : forall (x : FSet A),
-  apD FSet_ind (nr x) = (nrP x (FSet_ind x)).
-
-Axiom FSet_ind_beta_idem : forall (x : A), apD FSet_ind (idem x) = idemP x.
-End FSet_induction.
-
-Section FSet_recursion.
-
-Variable A : Type.
-Variable P : Type.
-Variable e : P.
-Variable l : A -> P.
-Variable u : P -> P -> P.
-Variable assocP : forall (x y z : P), u x (u y z) = u (u x y) z.
-Variable commP : forall (x y : P), u x y = u y x.
-Variable nlP : forall (x : P), u e x = x.
-Variable nrP : forall (x : P), u x e = x.
-Variable idemP : forall (x : A), u (l x) (l x) = l x.
-
-Definition FSet_rec : FSet A -> P.
-Proof.
-simple refine (FSet_ind A _ _ _ _ _ _ _ _ _) ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
-- apply e.
-- apply l.
-- intros x y ; apply u.
-- apply assocP.
-- apply commP.
-- apply nlP.
-- apply nrP.
-- apply idemP.
-Defined.
-
-Definition FSet_rec_beta_assoc : forall (x y z : FSet A),
-  ap FSet_rec (assoc x y z) 
-  =
-  assocP (FSet_rec x) (FSet_rec y) (FSet_rec z).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (assoc x y z) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_assoc.
-Defined.
-
-Definition FSet_rec_beta_comm : forall (x y : FSet A),
-  ap FSet_rec (comm x y) 
-  =
-  commP (FSet_rec x) (FSet_rec y).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (comm x y) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_comm.
-Defined.
-
-Definition FSet_rec_beta_nl : forall (x : FSet A),
-  ap FSet_rec (nl x) 
-  =
-  nlP (FSet_rec x).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (nl x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_nl.
-Defined.
-
-Definition FSet_rec_beta_nr : forall (x : FSet A),
-  ap FSet_rec (nr x) 
-  =
-  nrP (FSet_rec x).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (nr x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_nr.
-Defined.
-
-Definition FSet_rec_beta_idem : forall (a : A),
-  ap FSet_rec (idem a) 
-  =
-  idemP a.
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (idem a) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_idem.
-Defined.
   
-End FSet_recursion.
+  Section FSet.
+    Variable A : Type.
 
-Instance FSet_recursion A : HitRecursion (FSet A) := {
-  indTy := _; recTy := _; 
-  H_inductor := FSet_ind A; H_recursor := FSet_rec A }.
+    Private Inductive FSet : Type :=
+    | E : FSet
+    | L : A -> FSet
+    | U : FSet -> FSet -> FSet.
+
+    Notation "{| x |}" :=  (L x).
+    Infix "∪" := U (at level 8, right associativity).
+    Notation "∅" := E.
+
+    Axiom assoc : forall (x y z : FSet ),
+        x ∪ (y ∪ z) = (x ∪ y) ∪ z.
+
+    Axiom comm : forall (x y : FSet),
+        x ∪ y = y ∪ x.
+
+    Axiom nl : forall (x : FSet),
+        ∅ ∪ x = x.
+
+    Axiom nr : forall (x : FSet),
+        x ∪ ∅ = x.
+
+    Axiom idem : forall (x : A),
+        {| x |} ∪ {|x|} = {|x|}.
+
+  End FSet.
+
+  Arguments E {_}.
+  Arguments U {_} _ _.
+  Arguments L {_} _.
+  Arguments assoc {_} _ _ _.
+  Arguments comm {_} _ _.
+  Arguments nl {_} _.
+  Arguments nr {_} _.
+  Arguments idem {_} _.
+
+  Section FSet_induction.
+    Variable A: Type.
+    Variable  (P : FSet A -> Type).
+    Variable  (eP : P E).
+    Variable  (lP : forall a: A, P (L a)).
+    Variable  (uP : forall (x y: FSet A), P x -> P y -> P (U x y)).
+    Variable  (assocP : forall (x y z : FSet A) 
+                               (px: P x) (py: P y) (pz: P z),
+                  assoc x y z #
+                        (uP      x    (U y z)          px        (uP y z py pz)) 
+                  = 
+                  (uP   (U x y)    z       (uP x y px py)          pz)).
+    Variable  (commP : forall (x y: FSet A) (px: P x) (py: P y),
+                  comm x y #
+                       uP x y px py = uP y x py px).
+    Variable  (nlP : forall (x : FSet A) (px: P x), 
+                  nl x # uP E x eP px = px).
+    Variable  (nrP : forall (x : FSet A) (px: P x), 
+                  nr x # uP x E px eP = px).
+    Variable  (idemP : forall (x : A), 
+                  idem x # uP (L x) (L x) (lP x) (lP x) = lP x).
+
+    (* Induction principle *)
+    Fixpoint FSet_ind
+             (x : FSet A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> _ -> _ -> P x with
+          | E => fun _ => fun _ => fun _ => fun _ => fun _ => eP
+          | L a => fun _ => fun _ => fun _ => fun _ => fun _ => lP a
+          | U y z => fun _ => fun _ => fun _ => fun _ => fun _ => uP y z
+                                                                     (FSet_ind y)
+                                                                     (FSet_ind z)
+          end) assocP commP nlP nrP idemP.
+
+
+    Axiom FSet_ind_beta_assoc : forall (x y z : FSet A),
+        apD FSet_ind (assoc x y z) =
+        (assocP x y z (FSet_ind x)  (FSet_ind y) (FSet_ind z)).
+
+    Axiom FSet_ind_beta_comm : forall (x y : FSet A),
+        apD FSet_ind (comm x y) = (commP x y (FSet_ind x) (FSet_ind y)).
+
+    Axiom FSet_ind_beta_nl : forall (x : FSet A),
+        apD FSet_ind (nl x) = (nlP x (FSet_ind x)).
+
+    Axiom FSet_ind_beta_nr : forall (x : FSet A),
+        apD FSet_ind (nr x) = (nrP x (FSet_ind x)).
+
+    Axiom FSet_ind_beta_idem : forall (x : A), apD FSet_ind (idem x) = idemP x.
+  End FSet_induction.
+
+  Section FSet_recursion.
+
+    Variable A : Type.
+    Variable P : Type.
+    Variable e : P.
+    Variable l : A -> P.
+    Variable u : P -> P -> P.
+    Variable assocP : forall (x y z : P), u x (u y z) = u (u x y) z.
+    Variable commP : forall (x y : P), u x y = u y x.
+    Variable nlP : forall (x : P), u e x = x.
+    Variable nrP : forall (x : P), u x e = x.
+    Variable idemP : forall (x : A), u (l x) (l x) = l x.
+
+    Definition FSet_rec : FSet A -> P.
+    Proof.
+      simple refine (FSet_ind A _ _ _ _ _ _ _ _ _) ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
+      - apply e.
+      - apply l.
+      - intros x y ; apply u.
+      - apply assocP.
+      - apply commP.
+      - apply nlP.
+      - apply nrP.
+      - apply idemP.
+    Defined.
+
+    Definition FSet_rec_beta_assoc : forall (x y z : FSet A),
+        ap FSet_rec (assoc x y z) 
+        =
+        assocP (FSet_rec x) (FSet_rec y) (FSet_rec z).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (assoc x y z) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_assoc.
+    Defined.
+
+    Definition FSet_rec_beta_comm : forall (x y : FSet A),
+        ap FSet_rec (comm x y) 
+        =
+        commP (FSet_rec x) (FSet_rec y).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (comm x y) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_comm.
+    Defined.
+
+    Definition FSet_rec_beta_nl : forall (x : FSet A),
+        ap FSet_rec (nl x) 
+        =
+        nlP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nl x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nl.
+    Defined.
+
+    Definition FSet_rec_beta_nr : forall (x : FSet A),
+        ap FSet_rec (nr x) 
+        =
+        nrP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nr x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nr.
+    Defined.
+
+    Definition FSet_rec_beta_idem : forall (a : A),
+        ap FSet_rec (idem a) 
+        =
+        idemP a.
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (idem a) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_idem.
+    Defined.
+    
+  End FSet_recursion.
+
+  Instance FSet_recursion A : HitRecursion (FSet A) := {
+                                                        indTy := _; recTy := _; 
+                                                        H_inductor := FSet_ind A; H_recursor := FSet_rec A }.
 
 End FSet.
 
@@ -194,104 +194,104 @@ Infix "∪" := U (at level 8, right associativity).
 Notation "∅" := E.
 
 Section set_sphere.
-From HoTT.HIT Require Import Circle.
-From HoTT Require Import UnivalenceAxiom.
-Instance S1_recursion : HitRecursion S1 := {
-  indTy := _; recTy := _; 
-  H_inductor := S1_ind; H_recursor := S1_rec }.
+  From HoTT.HIT Require Import Circle.
+  From HoTT Require Import UnivalenceAxiom.
+  Instance S1_recursion : HitRecursion S1 := {
+                                              indTy := _; recTy := _; 
+                                              H_inductor := S1_ind; H_recursor := S1_rec }.
 
-Variable A : Type.
+  Variable A : Type.
 
-Definition f (x : S1) : x = x.
-Proof.
-hrecursion x.
-- exact loop.
-- etransitivity. 
-  eapply (@transport_paths_FlFr S1 S1 idmap idmap).
-  hott_simpl.
-Defined.
+  Definition f (x : S1) : x = x.
+  Proof.
+    hrecursion x.
+    - exact loop.
+    - etransitivity. 
+      eapply (@transport_paths_FlFr S1 S1 idmap idmap).
+      hott_simpl.
+  Defined.
 
-Definition S1op (x y : S1) : S1.
-Proof.
-hrecursion y.
-- exact x. (* x + base = x *)
-- apply f. 
-Defined.
+  Definition S1op (x y : S1) : S1.
+  Proof.
+    hrecursion y.
+    - exact x. (* x + base = x *)
+    - apply f. 
+  Defined.
 
-Lemma S1op_nr (x : S1) : S1op x base = x.
-Proof. reflexivity. Defined.
+  Lemma S1op_nr (x : S1) : S1op x base = x.
+  Proof. reflexivity. Defined.
 
-Lemma S1op_nl (x : S1) : S1op base x = x.
-Proof.
-hrecursion x.
-- exact loop.
-- etransitivity.
-  apply (@transport_paths_FlFr _ _ (fun x => S1op base x) idmap _ _ loop loop).
-  hott_simpl.
-  apply moveR_pM. apply moveR_pM. hott_simpl.
-  etransitivity. apply (ap_V (S1op base) loop).
-  f_ap. apply S1_rec_beta_loop.
-Defined.
+  Lemma S1op_nl (x : S1) : S1op base x = x.
+  Proof.
+    hrecursion x.
+    - exact loop.
+    - etransitivity.
+      apply (@transport_paths_FlFr _ _ (fun x => S1op base x) idmap _ _ loop loop).
+      hott_simpl.
+      apply moveR_pM. apply moveR_pM. hott_simpl.
+      etransitivity. apply (ap_V (S1op base) loop).
+      f_ap. apply S1_rec_beta_loop.
+  Defined.
 
-Lemma S1op_assoc (x y z : S1) : S1op x (S1op y z) = S1op (S1op x y) z.
-Proof.
-hrecursion z.
-- reflexivity.
-- etransitivity.
-  apply (@transport_paths_FlFr _ _ (fun z => S1op x (S1op y z)) (S1op (S1op x y)) _ _ loop idpath). 
-  hott_simpl.
-  apply moveR_Mp. hott_simpl.
-  rewrite S1_rec_beta_loop.
-  rewrite ap_compose.
-  rewrite S1_rec_beta_loop.
-  hrecursion y.
-  + symmetry. apply S1_rec_beta_loop.
-  + apply is1type_S1. 
-Qed.
+  Lemma S1op_assoc (x y z : S1) : S1op x (S1op y z) = S1op (S1op x y) z.
+  Proof.
+    hrecursion z.
+    - reflexivity.
+    - etransitivity.
+      apply (@transport_paths_FlFr _ _ (fun z => S1op x (S1op y z)) (S1op (S1op x y)) _ _ loop idpath). 
+      hott_simpl.
+      apply moveR_Mp. hott_simpl.
+      rewrite S1_rec_beta_loop.
+      rewrite ap_compose.
+      rewrite S1_rec_beta_loop.
+      hrecursion y.
+      + symmetry. apply S1_rec_beta_loop.
+      + apply is1type_S1. 
+  Qed.
 
-Lemma S1op_comm (x y : S1) : S1op x y = S1op y x.
-Proof.
-hrecursion x.
-- apply S1op_nl.
-- hrecursion y.
-  + rewrite transport_paths_FlFr. hott_simpl. 
-    rewrite S1_rec_beta_loop. reflexivity.
-  + apply is1type_S1.
-Defined.
+  Lemma S1op_comm (x y : S1) : S1op x y = S1op y x.
+  Proof.
+    hrecursion x.
+    - apply S1op_nl.
+    - hrecursion y.
+      + rewrite transport_paths_FlFr. hott_simpl. 
+        rewrite S1_rec_beta_loop. reflexivity.
+      + apply is1type_S1.
+  Defined.
 
-Definition FSet_to_S : FSet A -> S1.
-Proof.
-hrecursion.
-- exact base.
-- intro a. exact base.
-- exact S1op.
-- apply S1op_assoc.
-- apply S1op_comm.
-- apply S1op_nl.
-- apply S1op_nr.
-- simpl. reflexivity.
-Defined.
+  Definition FSet_to_S : FSet A -> S1.
+  Proof.
+    hrecursion.
+    - exact base.
+    - intro a. exact base.
+    - exact S1op.
+    - apply S1op_assoc.
+    - apply S1op_comm.
+    - apply S1op_nl.
+    - apply S1op_nr.
+    - simpl. reflexivity.
+  Defined.
 
-Lemma FSet_S_ap : (nl (@E A)) = (nr E) -> idpath = loop.
-Proof.
-intros H.
-enough (ap FSet_to_S (nl E) = ap FSet_to_S (nr E)) as H'.
-- rewrite FSet_rec_beta_nl in H'. 
-  rewrite FSet_rec_beta_nr in H'.
-  simpl in H'. unfold S1op_nr in H'.
-  exact H'^.
-- f_ap.
-Defined.
+  Lemma FSet_S_ap : (nl (@E A)) = (nr E) -> idpath = loop.
+  Proof.
+    intros H.
+    enough (ap FSet_to_S (nl E) = ap FSet_to_S (nr E)) as H'.
+    - rewrite FSet_rec_beta_nl in H'. 
+      rewrite FSet_rec_beta_nr in H'.
+      simpl in H'. unfold S1op_nr in H'.
+      exact H'^.
+    - f_ap.
+  Defined.
 
-Lemma FSet_not_hset : IsHSet (FSet A) -> False.
-Proof.
-intros H.
-enough (idpath = loop). 
-- assert (S1_encode _ idpath = S1_encode _ (loopexp loop (pos Int.one))) as H' by f_ap.
-  rewrite S1_encode_loopexp in H'. simpl in H'. symmetry in H'.
-  apply (pos_neq_zero H').
-- apply FSet_S_ap.
-  apply set_path2.
-Qed.
+  Lemma FSet_not_hset : IsHSet (FSet A) -> False.
+  Proof.
+    intros H.
+    enough (idpath = loop). 
+    - assert (S1_encode _ idpath = S1_encode _ (loopexp loop (pos Int.one))) as H' by f_ap.
+      rewrite S1_encode_loopexp in H'. simpl in H'. symmetry in H'.
+      apply (pos_neq_zero H').
+    - apply FSet_S_ap.
+      apply set_path2.
+  Qed.
 
 End set_sphere.
diff --git a/FiniteSets/representations/cons_repr.v b/FiniteSets/representations/cons_repr.v
index 87b592e..ec150e6 100644
--- a/FiniteSets/representations/cons_repr.v
+++ b/FiniteSets/representations/cons_repr.v
@@ -1,323 +1,116 @@
+(* Definition of Finite Sets as via cons lists *)
 Require Import HoTT HitTactics.
-Require Import representations.definition.
-From fsets Require Import operations_decidable properties_decidable.
 
 Module Export FSetC.
- 
-Section FSetC.
-Variable A : Type.
+  
+  Section FSetC.
+    Variable A : Type.
 
-Private Inductive FSetC : Type :=
-  | Nil : FSetC
-  | Cns : A ->  FSetC -> FSetC.
+    Private Inductive FSetC : Type :=
+    | Nil : FSetC
+    | Cns : A ->  FSetC -> FSetC.
 
-Infix ";;" := Cns (at level 8, right associativity).
-Notation "∅" := Nil.
+    Infix ";;" := Cns (at level 8, right associativity).
+    Notation "∅" := Nil.
 
-Axiom dupl : forall (a: A) (x: FSetC),
-  a ;; a ;; x = a ;; x. 
+    Axiom dupl : forall (a: A) (x: FSetC),
+        a ;; a ;; x = a ;; x. 
 
-Axiom comm : forall (a b: A) (x: FSetC),
-   a ;; b ;; x = b ;; a ;; x.
+    Axiom comm : forall (a b: A) (x: FSetC),
+        a ;; b ;; x = b ;; a ;; x.
 
-Axiom trunc : IsHSet FSetC.
+    Axiom trunc : IsHSet FSetC.
+
+  End FSetC.
+
+  Arguments Nil {_}.
+  Arguments Cns {_} _ _.
+  Arguments dupl {_} _ _.
+  Arguments comm {_} _ _ _.
+
+  Infix ";;" := Cns (at level 8, right associativity).
+  Notation "∅" := Nil.
+
+  Section FSetC_induction.
+
+    Variable A: Type.
+    Variable (P : FSetC A -> Type).
+    Variable (H :  forall x : FSetC A, IsHSet (P x)).
+    Variable (eP : P ∅).
+    Variable (cnsP : forall (a:A) (x: FSetC A), P x -> P (a ;; x)).
+    Variable (duplP : forall (a: A) (x: FSetC A) (px : P x),
+	         dupl a x # cnsP a (a;;x) (cnsP a x px) = cnsP a x px).
+    Variable (commP : forall (a b: A) (x: FSetC A) (px: P x),
+		 comm a b x # cnsP a (b;;x) (cnsP b x px) = 
+		 cnsP b (a;;x) (cnsP a x px)).
+    
+    (* Induction principle *)
+    Fixpoint FSetC_ind
+             (x : FSetC A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> P x with
+          | Nil => fun _ => fun _ => fun _  => eP
+          | a ;; y => fun _ => fun _ => fun _ => cnsP a y (FSetC_ind y)
+          end) H duplP commP.
+
+
+    Axiom FSetC_ind_beta_dupl : forall (a: A) (x : FSetC A),
+        apD FSetC_ind (dupl a x) = 	duplP a x (FSetC_ind x).
+
+    Axiom FSetC_ind_beta_comm : forall (a b: A) (x : FSetC A),
+        apD FSetC_ind (comm a b x) = commP a b x (FSetC_ind x).
+
+  End FSetC_induction.
+
+  Section FSetC_recursion.
+
+    Variable A: Type.
+    Variable (P: Type).
+    Variable (H: IsHSet P).
+    Variable (nil : P).
+    Variable (cns :  A -> P -> P).
+    Variable (duplP : forall (a: A) (x: P), cns a (cns a x) = (cns a x)).
+    Variable (commP : forall (a b: A) (x: P), cns a (cns b x) = cns b (cns a x)).
+
+    (* Recursion principle *)
+    Definition FSetC_rec : FSetC A -> P.
+    Proof.
+      simple refine (FSetC_ind _ _ _ _ _  _ _ ); 
+        try (intros; simple refine ((transport_const _ _) @ _ ));  cbn.
+      - apply nil.
+      - apply 	(fun a => fun _ => cns a). 
+      - apply duplP.
+      - apply commP. 
+    Defined.
+
+
+    Definition FSetC_rec_beta_dupl : forall (a: A) (x : FSetC A),
+        ap FSetC_rec (dupl a x) = duplP a (FSetC_rec x).
+    Proof.
+      intros. 
+      eapply (cancelL (transport_const (dupl a x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSetC_ind_beta_dupl.
+    Defined.
+
+    Definition FSetC_rec_beta_comm : forall (a b: A) (x : FSetC A),
+        ap FSetC_rec (comm a b x) = commP a b (FSetC_rec x).
+    Proof.
+      intros. 
+      eapply (cancelL (transport_const (comm a b x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSetC_ind_beta_comm.
+    Defined.
+
+  End FSetC_recursion.
+
+
+  Instance FSetC_recursion A : HitRecursion (FSetC A) := {
+                                                          indTy := _; recTy := _; 
+                                                          H_inductor := FSetC_ind A; H_recursor := FSetC_rec A }.
 
 End FSetC.
 
-Arguments Nil {_}.
-Arguments Cns {_} _ _.
-Arguments dupl {_} _ _.
-Arguments comm {_} _ _ _.
-
 Infix ";;" := Cns (at level 8, right associativity).
-Notation "∅" := Nil.
-
-Section FSetC_induction.
-
-Variable A: Type.
-Variable (P : FSetC A -> Type).
-Variable (H :  forall x : FSetC A, IsHSet (P x)).
-Variable (eP : P ∅).
-Variable (cnsP : forall (a:A) (x: FSetC A), P x -> P (a ;; x)).
-Variable (duplP : forall (a: A) (x: FSetC A) (px : P x),
-	          dupl a x # cnsP a (a;;x) (cnsP a x px) = cnsP a x px).
-Variable (commP : forall (a b: A) (x: FSetC A) (px: P x),
-			     comm a b x # cnsP a (b;;x) (cnsP b x px) = 
-			     cnsP b (a;;x) (cnsP a x px)).
-			     
-(* Induction principle *)
-Fixpoint FSetC_ind
-  (x : FSetC A)
-  {struct x}
-  : P x
-  := (match x return _ -> _ -> _ -> P x with
-        | Nil => fun _ => fun _ => fun _  => eP
-        | a ;; y => fun _ => fun _ => fun _ => cnsP a y (FSetC_ind y)
-      end) H duplP commP.
-
-
-Axiom FSetC_ind_beta_dupl : forall (a: A) (x : FSetC A),
-  apD FSetC_ind (dupl a x) = 	duplP a x (FSetC_ind x).
-
-Axiom FSetC_ind_beta_comm : forall (a b: A) (x : FSetC A),
-  apD FSetC_ind (comm a b x) = commP a b x (FSetC_ind x).
-
-End FSetC_induction.
-
-Section FSetC_recursion.
-
-Variable A: Type.
-Variable (P: Type).
-Variable (H: IsHSet P).
-Variable (nil : P).
-Variable (cns :  A -> P -> P).
-Variable (duplP : forall (a: A) (x: P), cns a (cns a x) = (cns a x)).
-Variable (commP : forall (a b: A) (x: P), cns a (cns b x) = cns b (cns a x)).
-
-(* Recursion principle *)
-Definition FSetC_rec : FSetC A -> P.
-Proof.
-simple refine (FSetC_ind _ _ _ _ _  _ _ ); 
-try (intros; simple refine ((transport_const _ _) @ _ ));  cbn.
-- apply nil.
-- apply 	(fun a => fun _ => cns a). 
-- apply duplP.
-- apply commP. 
-Defined.
-
-
-Definition FSetC_rec_beta_dupl : forall (a: A) (x : FSetC A),
-  ap FSetC_rec (dupl a x) = duplP a (FSetC_rec x).
-Proof.
-intros. 
-unfold FSet_rec.
-eapply (cancelL (transport_const (dupl a x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSetC_ind_beta_dupl.
-Defined.
-
-Definition FSetC_rec_beta_comm : forall (a b: A) (x : FSetC A),
-  ap FSetC_rec (comm a b x) = commP a b (FSetC_rec x).
-Proof.
-intros. 
-unfold FSet_rec.
-eapply (cancelL (transport_const (comm a b x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSetC_ind_beta_comm.
-Defined.
-
-End FSetC_recursion.
-
-
-Instance FSetC_recursion A : HitRecursion (FSetC A) := {
-  indTy := _; recTy := _; 
-  H_inductor := FSetC_ind A; H_recursor := FSetC_rec A }.
-
-
-
-
-
-Section Append.
-
-Context {A : Type}.
-Context {A_deceq : DecidablePaths A}.
-
-Definition append  (x y: FSetC A) : FSetC A.
-hinduction x.
-- apply y.
-- apply Cns.
-- apply dupl.
-- apply comm.
-Defined.
-
-
-Lemma append_nl: 
-  forall (x: FSetC A), append ∅ x = x. 
-Proof.
-  intro. reflexivity.
-Defined.
-
-Lemma append_nr: 
-  forall (x: FSetC A), append x ∅ = x.
-Proof.
-  hinduction; try (intros; apply set_path2).
-  -  reflexivity.
-  -  intros. apply (ap (fun y => a ;; y) X).
-Defined.
- 
-Lemma append_assoc {H: Funext}:  
-  forall (x y z: FSetC A), append x (append y z) = append (append x y) z.
-Proof.
-  intro x; hinduction x; try (intros; apply set_path2).
-  - reflexivity.
-  - intros a x HR y z. 
-    specialize (HR y z).
-    apply (ap (fun y => a ;; y) HR). 
-  - intros. apply path_forall. 
-  	  intro. apply path_forall. 
-  	  intro. apply set_path2.
-  - intros. apply path_forall.
-    intro. apply path_forall. 
-  	  intro. apply set_path2.
-Defined.
-      
- Lemma aux: forall (a: A) (x: FSetC A), 
-   a ;; x = append x (a ;; ∅).
-Proof.
-intro a. hinduction; try (intros; apply set_path2).
-- reflexivity.
-- intros b x HR. refine (_ @ _).
-	+ apply comm.
-	+ apply (ap (fun y => b ;; y) HR).
-Defined.
-
-
-Lemma append_comm {H: Funext}: 
-  forall (x1 x2: FSetC A), append x1 x2 = append x2 x1.
-Proof.
-  intro x1. 
-  hinduction x1;  try (intros; apply set_path2).
-  - intros. symmetry. apply append_nr. 
-  - intros a x1 HR x2.
-    etransitivity.
-    apply (ap (fun y => a;;y) (HR x2)).  
-    transitivity  (append (append x2 x1) (a;;∅)).
-    + apply aux. 
-    + etransitivity.
-    	  * symmetry. apply append_assoc.
-    	  * simple refine (ap (fun y => append x2 y) (aux _ _)^).
-  - intros. apply path_forall.
-    intro. apply set_path2.
-  - intros. apply path_forall.
-    intro. apply set_path2.  
-Defined.
-
-
-End Append.
-
-
-Section Singleton.
-
-Context {A : Type}.
-Context {A_deceq : DecidablePaths A}.
-
-Definition singleton (a:A) : FSetC A := a;;∅.
-
-Lemma singleton_idem: forall (a: A), 
-  append (singleton a) (singleton a) = singleton a.
-Proof.
-unfold singleton. intro. cbn. apply dupl.
-Defined.
-
-End Singleton.
-
-
-
-Infix ";;" := Cns (at level 8, right associativity).
-Notation "∅" := Nil.
-
-End FSetC.
-
-
-Section Iso.
-
-Context {A : Type}.
-Context {A_deceq : DecidablePaths A}.
-Context {H : Funext}.
-
-
-Definition FSetC_to_FSet: FSetC A -> FSet A.
-Proof.
-hrecursion.
-- apply E.
-- intros a x. apply (U (L a) x).
-- intros. cbn.  
-	etransitivity. apply assoc.
-	apply (ap (fun y => U y x)).
-	apply idem.
-- intros. cbn.
- etransitivity. apply assoc.
- etransitivity. refine (ap (fun y => U y x) _ ).
- apply FSet.comm.
- symmetry. 
- apply assoc.
-Defined.
-
-Definition FSet_to_FSetC: FSet A -> FSetC A :=
-  FSet_rec A (FSetC A) (trunc A) ∅ singleton append append_assoc 
-    append_comm append_nl append_nr singleton_idem.
-
-
-Lemma append_union: forall (x y: FSetC A), 
-  FSetC_to_FSet (append x y) = U (FSetC_to_FSet x) (FSetC_to_FSet y).
-Proof.
-intros x. 
-hrecursion x; try (intros; apply path_forall; intro; apply set_path2).
-- intros. symmetry. apply nl.
-- intros a x HR y. rewrite HR. apply assoc.
-Defined.
-
-Lemma repr_iso_id_l: forall (x: FSet A), FSetC_to_FSet (FSet_to_FSetC x) = x.
-Proof.
-hinduction; try (intros; apply set_path2).
-- reflexivity.
-- intro. apply nr.
-- intros x y p q. rewrite append_union, p, q. reflexivity.
-Defined.
-
-
-Lemma repr_iso_id_r: forall (x: FSetC A), FSet_to_FSetC (FSetC_to_FSet x) = x.
-Proof.
-hinduction; try (intros; apply set_path2).
-- reflexivity.
-- intros a x HR. rewrite HR. reflexivity.
-Defined.
-
-
-Theorem repr_iso: FSet A <~> FSetC A.
-Proof.
-simple refine (@BuildEquiv (FSet A) (FSetC A) FSet_to_FSetC _ ).
-apply isequiv_biinv.
-unfold BiInv. split.
-exists FSetC_to_FSet.
-unfold Sect. apply repr_iso_id_l.
-exists FSetC_to_FSet.
-unfold Sect. apply repr_iso_id_r.
-Defined.
-
-End Iso.
-
-Section Length.
-
-Context {A : Type}.
-Context {A_deceq : DecidablePaths A}.
-Context `{Univalence}.
-
-Opaque isIn_b.
-Definition length (x: FSetC A) : nat.
-Proof.
-simple refine (FSetC_ind A _ _ _ _ _ _ x ); simpl.
-- exact 0.
-- intros a y n. 
-  pose (y' := FSetC_to_FSet y).
-  exact (if isIn_b a y' then n else (S n)).
-- intros. rewrite transport_const. cbn.
-  simplify_isIn. simpl. reflexivity.
-- intros. rewrite transport_const. cbn.
-  simplify_isIn.
-  destruct (dec (a = b)) as [Hab | Hab].
-  + rewrite Hab. simplify_isIn. simpl. reflexivity.
-  + rewrite ?L_isIn_b_false; auto. simpl. 
-    destruct (isIn_b a (FSetC_to_FSet x0)), (isIn_b b (FSetC_to_FSet x0)) ; reflexivity.
-    intro p. contradiction (Hab p^).
-Defined.
-
-Definition length_FSet (x: FSet A) := length (FSet_to_FSetC x).
-
-Lemma length_singleton: forall (a: A), length_FSet (L a) = 1.
-Proof. 
-intro a.
-cbn. reflexivity. 
-Defined.
-
-End Length.
+Notation "∅" := Nil.
\ No newline at end of file
diff --git a/FiniteSets/representations/definition.v b/FiniteSets/representations/definition.v
index ea167b4..5c6848a 100644
--- a/FiniteSets/representations/definition.v
+++ b/FiniteSets/representations/definition.v
@@ -3,190 +3,189 @@ Require Import HoTT.
 Require Import HitTactics.
 
 Module Export FSet.
- 
-Section FSet.
-Variable A : Type.
+  Section FSet.
+    Variable A : Type.
 
-Private Inductive FSet : Type :=
-  | E : FSet
-  | L : A -> FSet
-  | U : FSet -> FSet -> FSet.
+    Private Inductive FSet : Type :=
+    | E : FSet
+    | L : A -> FSet
+    | U : FSet -> FSet -> FSet.
 
-Notation "{| x |}" :=  (L x).
-Infix "∪" := U (at level 8, right associativity).
-Notation "∅" := E.
+    Notation "{| x |}" :=  (L x).
+    Infix "∪" := U (at level 8, right associativity).
+    Notation "∅" := E.
 
-Axiom assoc : forall (x y z : FSet ),
-  x ∪ (y ∪ z) = (x ∪ y) ∪ z.
+    Axiom assoc : forall (x y z : FSet ),
+        x ∪ (y ∪ z) = (x ∪ y) ∪ z.
 
-Axiom comm : forall (x y : FSet),
-  x ∪ y = y ∪ x.
+    Axiom comm : forall (x y : FSet),
+        x ∪ y = y ∪ x.
 
-Axiom nl : forall (x : FSet),
-  ∅ ∪ x = x.
+    Axiom nl : forall (x : FSet),
+        ∅ ∪ x = x.
 
-Axiom nr : forall (x : FSet),
-  x ∪ ∅ = x.
+    Axiom nr : forall (x : FSet),
+        x ∪ ∅ = x.
 
-Axiom idem : forall (x : A),
-  {| x |} ∪ {|x|} = {|x|}.
+    Axiom idem : forall (x : A),
+        {| x |} ∪ {|x|} = {|x|}.
 
-Axiom trunc : IsHSet FSet.
+    Axiom trunc : IsHSet FSet.
 
-End FSet.
+  End FSet.
 
-Arguments E {_}.
-Arguments U {_} _ _.
-Arguments L {_} _.
-Arguments assoc {_} _ _ _.
-Arguments comm {_} _ _.
-Arguments nl {_} _.
-Arguments nr {_} _.
-Arguments idem {_} _.
+  Arguments E {_}.
+  Arguments U {_} _ _.
+  Arguments L {_} _.
+  Arguments assoc {_} _ _ _.
+  Arguments comm {_} _ _.
+  Arguments nl {_} _.
+  Arguments nr {_} _.
+  Arguments idem {_} _.
 
-Section FSet_induction.
-Variable A: Type.
-Variable  (P : FSet A -> Type).
-Variable  (H :  forall a : FSet A, IsHSet (P a)).
-Variable  (eP : P E).
-Variable  (lP : forall a: A, P (L a)).
-Variable  (uP : forall (x y: FSet A), P x -> P y -> P (U x y)).
-Variable  (assocP : forall (x y z : FSet A) 
-                   (px: P x) (py: P y) (pz: P z),
-  assoc x y z #
-   (uP      x    (U y z)          px        (uP y z py pz)) 
-  = 
-   (uP   (U x y)    z       (uP x y px py)          pz)).
-Variable  (commP : forall (x y: FSet A) (px: P x) (py: P y),
-  comm x y #
-  uP x y px py = uP y x py px).
-Variable  (nlP : forall (x : FSet A) (px: P x), 
-  nl x # uP E x eP px = px).
-Variable  (nrP : forall (x : FSet A) (px: P x), 
-  nr x # uP x E px eP = px).
-Variable  (idemP : forall (x : A), 
-  idem x # uP (L x) (L x) (lP x) (lP x) = lP x).
+  Section FSet_induction.
+    Variable A: Type.
+    Variable  (P : FSet A -> Type).
+    Variable  (H :  forall a : FSet A, IsHSet (P a)).
+    Variable  (eP : P E).
+    Variable  (lP : forall a: A, P (L a)).
+    Variable  (uP : forall (x y: FSet A), P x -> P y -> P (U x y)).
+    Variable  (assocP : forall (x y z : FSet A) 
+                               (px: P x) (py: P y) (pz: P z),
+                  assoc x y z #
+                        (uP      x    (U y z)          px        (uP y z py pz)) 
+                  = 
+                  (uP   (U x y)    z       (uP x y px py)          pz)).
+    Variable  (commP : forall (x y: FSet A) (px: P x) (py: P y),
+                  comm x y #
+                       uP x y px py = uP y x py px).
+    Variable  (nlP : forall (x : FSet A) (px: P x), 
+                  nl x # uP E x eP px = px).
+    Variable  (nrP : forall (x : FSet A) (px: P x), 
+                  nr x # uP x E px eP = px).
+    Variable  (idemP : forall (x : A), 
+                  idem x # uP (L x) (L x) (lP x) (lP x) = lP x).
+    
+    (* Induction principle *)
+    Fixpoint FSet_ind
+             (x : FSet A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> _ -> _ -> _ -> P x with
+          | E => fun _ _ _ _ _ _ => eP
+          | L a => fun _ _ _ _ _ _ => lP a
+          | U y z => fun _ _ _ _ _ _ => uP y z (FSet_ind y) (FSet_ind z)
+          end) H assocP commP nlP nrP idemP.
 
-(* Induction principle *)
-Fixpoint FSet_ind
-  (x : FSet A)
-  {struct x}
-  : P x
-  := (match x return _ -> _ -> _ -> _ -> _ -> _ -> P x with
-      | E => fun _ _ _ _ _ _ => eP
-      | L a => fun _ _ _ _ _ _ => lP a
-      | U y z => fun _ _ _ _ _ _ => uP y z (FSet_ind y) (FSet_ind z)
-      end) H assocP commP nlP nrP idemP.
+    Axiom FSet_ind_beta_assoc : forall (x y z : FSet A),
+        apD FSet_ind (assoc x y z) =
+        (assocP x y z (FSet_ind x)  (FSet_ind y) (FSet_ind z)).
 
+    Axiom FSet_ind_beta_comm : forall (x y : FSet A),
+        apD FSet_ind (comm x y) = (commP x y (FSet_ind x) (FSet_ind y)).
 
-Axiom FSet_ind_beta_assoc : forall (x y z : FSet A),
-  apD FSet_ind (assoc x y z) =
-  (assocP x y z (FSet_ind x)  (FSet_ind y) (FSet_ind z)).
+    Axiom FSet_ind_beta_nl : forall (x : FSet A),
+        apD FSet_ind (nl x) = (nlP x (FSet_ind x)).
 
-Axiom FSet_ind_beta_comm : forall (x y : FSet A),
-  apD FSet_ind (comm x y) = (commP x y (FSet_ind x) (FSet_ind y)).
+    Axiom FSet_ind_beta_nr : forall (x : FSet A),
+        apD FSet_ind (nr x) = (nrP x (FSet_ind x)).
 
-Axiom FSet_ind_beta_nl : forall (x : FSet A),
-  apD FSet_ind (nl x) = (nlP x (FSet_ind x)).
+    Axiom FSet_ind_beta_idem : forall (x : A), apD FSet_ind (idem x) = idemP x.
+  End FSet_induction.
 
-Axiom FSet_ind_beta_nr : forall (x : FSet A),
-  apD FSet_ind (nr x) = (nrP x (FSet_ind x)).
+  Section FSet_recursion.
 
-Axiom FSet_ind_beta_idem : forall (x : A), apD FSet_ind (idem x) = idemP x.
-End FSet_induction.
+    Variable A : Type.
+    Variable P : Type.
+    Variable H: IsHSet P.
+    Variable e : P.
+    Variable l : A -> P.
+    Variable u : P -> P -> P.
+    Variable assocP : forall (x y z : P), u x (u y z) = u (u x y) z.
+    Variable commP : forall (x y : P), u x y = u y x.
+    Variable nlP : forall (x : P), u e x = x.
+    Variable nrP : forall (x : P), u x e = x.
+    Variable idemP : forall (x : A), u (l x) (l x) = l x.
 
-Section FSet_recursion.
+    Definition FSet_rec : FSet A -> P.
+    Proof.
+      simple refine (FSet_ind A _ _ _ _ _ _ _ _ _ _)
+      ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
+      - apply e.
+      - apply l.
+      - intros x y ; apply u.
+      - apply assocP.
+      - apply commP.
+      - apply nlP.
+      - apply nrP.
+      - apply idemP.
+    Defined.
 
-Variable A : Type.
-Variable P : Type.
-Variable H: IsHSet P.
-Variable e : P.
-Variable l : A -> P.
-Variable u : P -> P -> P.
-Variable assocP : forall (x y z : P), u x (u y z) = u (u x y) z.
-Variable commP : forall (x y : P), u x y = u y x.
-Variable nlP : forall (x : P), u e x = x.
-Variable nrP : forall (x : P), u x e = x.
-Variable idemP : forall (x : A), u (l x) (l x) = l x.
+    Definition FSet_rec_beta_assoc : forall (x y z : FSet A),
+        ap FSet_rec (assoc x y z) 
+        =
+        assocP (FSet_rec x) (FSet_rec y) (FSet_rec z).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (assoc x y z) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_assoc.
+    Defined.
 
-Definition FSet_rec : FSet A -> P.
-Proof.
-simple refine (FSet_ind A _ _ _ _ _ _ _ _ _ _) ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
-- apply e.
-- apply l.
-- intros x y ; apply u.
-- apply assocP.
-- apply commP.
-- apply nlP.
-- apply nrP.
-- apply idemP.
-Defined.
+    Definition FSet_rec_beta_comm : forall (x y : FSet A),
+        ap FSet_rec (comm x y) 
+        =
+        commP (FSet_rec x) (FSet_rec y).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (comm x y) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_comm.
+    Defined.
 
-Definition FSet_rec_beta_assoc : forall (x y z : FSet A),
-  ap FSet_rec (assoc x y z) 
-  =
-  assocP (FSet_rec x) (FSet_rec y) (FSet_rec z).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (assoc x y z) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_assoc.
-Defined.
+    Definition FSet_rec_beta_nl : forall (x : FSet A),
+        ap FSet_rec (nl x) 
+        =
+        nlP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nl x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nl.
+    Defined.
 
-Definition FSet_rec_beta_comm : forall (x y : FSet A),
-  ap FSet_rec (comm x y) 
-  =
-  commP (FSet_rec x) (FSet_rec y).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (comm x y) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_comm.
-Defined.
+    Definition FSet_rec_beta_nr : forall (x : FSet A),
+        ap FSet_rec (nr x) 
+        =
+        nrP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nr x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nr.
+    Defined.
 
-Definition FSet_rec_beta_nl : forall (x : FSet A),
-  ap FSet_rec (nl x) 
-  =
-  nlP (FSet_rec x).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (nl x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_nl.
-Defined.
+    Definition FSet_rec_beta_idem : forall (a : A),
+        ap FSet_rec (idem a) 
+        =
+        idemP a.
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (idem a) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_idem.
+    Defined.
+    
+  End FSet_recursion.
 
-Definition FSet_rec_beta_nr : forall (x : FSet A),
-  ap FSet_rec (nr x) 
-  =
-  nrP (FSet_rec x).
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (nr x) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_nr.
-Defined.
-
-Definition FSet_rec_beta_idem : forall (a : A),
-  ap FSet_rec (idem a) 
-  =
-  idemP a.
-Proof.
-intros.
-unfold FSet_rec.
-eapply (cancelL (transport_const (idem a) _)).
-simple refine ((apD_const _ _)^ @ _).
-apply FSet_ind_beta_idem.
-Defined.
-  
-End FSet_recursion.
-
-Instance FSet_recursion A : HitRecursion (FSet A) := {
-  indTy := _; recTy := _; 
-  H_inductor := FSet_ind A; H_recursor := FSet_rec A }.
+  Instance FSet_recursion A : HitRecursion (FSet A) := {
+                                                        indTy := _; recTy := _; 
+                                                        H_inductor := FSet_ind A; H_recursor := FSet_rec A }.
 
 End FSet.